Production of alkali metal oxides



2 Sheets-Sheet 1 INVENTOR.

ATTORNEY JOSHUA SZEGHTMAN GR ww J. SZECHTMAN PRODUCTION OF ALKALI METAL OXIDES IN1 uw QQ ym i Jan. 28, 1964 Filed March 8, 1961 Jan. 28, 1964 J. szEcHTMAN 3,119,664

PRODUCTION OF ALKALI METAL OXIDES Filed March 8, 1961 2 Sheets-Sheet 2 To cYcLoNE sEPARAToR .1, To AFTER cooLem; AND ExHAus'r. m

CALCIUM CHLORIDE AIR DRYER JOSHUA SZECHTMAN DISCHARGE BY 7 f A TTORNEX I INVENTOR.

United States Patent Oli ice 3,119,664 Patented Jan. 28, 1964 3,119,664 PRDUCTKUN F ALKALH METAL GXIDES Joshua Szechtman, Byrarn, Conn., assigner to Chlorrnctais incorporated, New York, NX., a corporation of Delaware Filed Mar. 3, 1961, Ser. No. 94,178 8 Claims. (Cl. 22a-134) This invention relates to the production of alkali metal oxides and is more particularly concerned with a process for producing alkali metal oxides at low cost in a single continuous process employing as the raw materials readily available alkali metal salt and dry air or oxygen.

This application is a continuation-impart application of my application Serial No. 699,979, filed December 2, 1957, and of my application Serial No. 22,1601, led April 14, 1960.

Alkali metal oxides such as monoxides, peroxides and the proper degree of oxidation is attained. In the case of sodium peroxide, sodium is produced by the electrolysis of sodium hydroxide in a cell of the Castner type, or by the electrolysis of sodium chloride in a cell of the Downs type. These known operations involve the melting of metallic sodium for the oxidation operation. in the case of potassium tetroxide, the process is even more complicated and costly because, in the initial step of producing metallic potassium, an electrolytic cell of the conventional type for electrolyzing fused salt, such as that of the Downs type, cannot be employed because the liberated potassium will come into Contact with the graphite anodes resulting in explosive reaction in the presence of air. In such case, therefore, the metallic potassium must first be obtained by melting potassium chloride and releasing the potassium therein by substitution of melted metallic sodium.

There is, therefore, an important need for a continuous and inexpensive process Which can effectively produce alkali metal oxides from readily available alkali metal salts and air.

it is, accordingly, an object of the present invention to provide a process for producing alkali metal oxides which avoids the drawbacks and disadvantages of processes heretofore employed.

it is a further object of the invention to provide a process of the character indicated by means of which alkali metal oxides can be produced without requiring the melting of solid alkali metal.

in accordance with the inv-ention, a readily available alkali metal salt, eg. potassium chloride is fused and then electrolyzed in the presence of a molten stream of lead, whereby the liberated alkali metal combines with the lead to form a lead alloy, which passes at high temperature from the electrolysis zone into a vaporizing zone where the alkali metal is vaporized from the lead, either by the addition of a relatively slight amount of heat, or by creating a partial vacuum in the vaporizing zone, or by a combination of both procedures. The alkali metal vapor is then passed directly to an oxidation zone wherein it is brought into Contact with oxygen or a `gaseous mixture containing oxygen, e.g. air, to produce solid alkali metal oxides which can be directly collected for packaging and shipment.

Other objects and features of the invention will be readily apparent `from the following detailed description of illustrati-ve embodiments thereof and from the accompanying drawing wherein,

FIG. 1 is an elevational view partly in section of an apparatus system particularly suitable for carrying out the process of the invention;

FIG. 2 is a sectional view on an enlarged scale of an apparatus for effecting oxidation of alkali metal;

FIG. 3 is a similar view of the oxidizer inlet construction; and

FIG. 4 is a sectional view showing details of baille construction.

Referring to the drawing, there is illustrated an electrolytic cell designated generally by the reference numeral lo. it will Ibe understood, however, that the invention is not limited to any specific cell construction and that any cell capable of producing an alloy of the alkali metal desired upon electrolysis of the corresponding salt may be employed. For example, there may suitably be used the cell described in my copending application Serial No. 699,979, vfiled December 2, 1957 (now U.S. Patent No. 3,104,213, dated September y17, 1963). Such a cell is particularly eiective for use in accordance with this invention since it produces a high quality lead-alkali metal alloy from which a substantially pure alkali metal vapor can be directly produced. Also particularly suitable `for use in connection with this invention is the improved cell l@ shown in the accompanying drawing which embodies all of the advantages of the cell of my said US. patent and, in addition, has further advantageous features. The cell body 12 of the cell l`1t) is suitably formed from metal, and is supported upon an insulation support 14, indicated in the drawing as refractory blocks or bricks, but it will be understood that any other convenient insulating base may be employed. As seen in FIG. l, the cell 1li deines a sole surface 15 upon which the liquid cathode 16, c g. l

molten lead, is adapted to rest and to flow from left to right. Thus, the elongated cell body 12 is formed with an elongated channel of which the sole 15 is the bottom and which provides the electrolysis chamber 17. The `sole 15 may be horizontal or it may slope slightly toward the right. The slope of the sole may vary but a slope of 1 or less is preferred.

When the cell is operated at elevated temperatures for the electrolysis of molten salt, the molten salt and the liquid lead cathode are introduced into the cell at temperatures of about 8110 to 830 C. in the case of the electrolysis of molten sodium chloride, and the temperature prevailing in the electrolysis chamber is about 850. These temperatures will, of course, vary in the case of other alkali metal salts, depending upon the melting point of the salt and the boiling point of the alkali metal. Potassium chloride has a melting point of about 776 C. but the boiling point of potassium is about 760 C. Consequently the melting lpoint of the potassium salt is suitably lowered, e.g. to about 720 C. or below by adding to it suitable quantities of another salt, such as calcium chloride, and those amounts that do decompose are not absorbed by the lead. The amount of the added salt to be used will, of course, depend on the temperature to which the melting point is to be lowered and can be readily determined by routine test in each case.

Any convenient means for heating the cell body and maintaining it at the elevated temperature desired may be employed. Particularly effective is the heating means shown in the drawing wherein the cell body is formed with a plurality of longitudinally-extending conduits (one shown) which form a closed circuit with a heater 22 and a pump 24. These conduits are suitably filled with molten lead which is maintained at the desired temperature by the heater 22 and is then circulated through the cell body by means of the pump 24. Actually, the electrolysis reaction is exothermic but the heating means is provided in order to bring the cell to operating temperature when operation is begun and to minimize heat loss during operation so that the desired operating temperature is always maintained.

Closing the cell is a cover which extends completely across the cell body i112 and also extends from one end of the cell body to the other. This cover is formed from an electrically-.conductive material and, most suitably, it is formed from graphite. As seen in the drawing, the cell body 12 is formed with a circumferentially-extending channel 34 which extends continuously around the side and end walls of 'the body 12. Channel 34 is adapted to be illed with a fluid which is liquid at cell-operating temperatures and, most advantageously, this tiuid is lead and the channel 34 communicates by means of suitable conduits (not shown) with the circuit which includes the conduits 20, the heater 22 and the pump 24. Depending from cover 30 into the channel 34 is a circumferential flange 42 which is embedded in the cover 30 and which extends downwardly a suiicient distance that its lower end rwill be immersed in the liquid 46 contained in the channel 34 in order to form a hydraulic seal. The flange 4Z is suitably formed from a material which is a non-conductor of electricity.

The cover 30 directly supports the anodes 50 and such support is etiected by means of anode stems 52. While in my said U.S. patent I show a conduit communicating with the electrolysis chamber for the removal of chlorine generated in the cell during electrolysis, provision may be made for withdrawing chlorine from the cell through the anodes and through the cover in the manner described in my co-pending application Serial No. 22,160, filed April 14, 1960. Thus, as seen in the drawing, the stems 52 are received in slots formed in the cover 30 and in the blocks so that these parts are removably connected only with the cover or only with the anodes, or all parts may be integrally interconnected. The anode blocks, the anode stems or supports, and the cover are provided with inter-communicating apertures and channels or passageways through which evolved gas is led from the site of evolution to a point exteriorly of the cell with minimum contact with contaminating surfaces.

The power connections are indicated diagrammatically at 56 and S7, but it will be understood that any conventional means may be employed to attach the power conductors, and a particularly suitable system is shown in my said U.S. patent. Similarly, the cover is suitably electrically insulated from the body of the cell and, since it is a conductor of electrolysis current, it is advantageously covered with electrical insulation, as shown in the drawing. ln addition, an insulating lining 60 is provided along the interior walls of the cell in the electrolysis chamber 17 and an insulating sheet 61 completely overlies the top edges of the wall of the cell body 12, being interruped only by the iiange 42. An auxiliary outlet channel 70, which may be stoppered to prevent ingress of air, is provided `in cover 30 to permit venting of the electrolysis chamber above the level of the electrolyte.

The manner in which the electrolyte and the liquid cathode are introduced into and removed from the cell form no part of the present invention but the manner described in my said U.S. patent is particularly suitable especially since it insures against entrance of air or oxygen with the electrolyte and the cathode into the electrolysis chamber. Thus, as seen in the drawing, the liquid cathode, eg. molten lead, and the electrolyte, e.g. molten alkali metal chloride, are introduced at the left-hand end of the cell body, the molten salt suitably being introduced through a conduit and the electrolyte being introduced through a conduit 82. The conduit 82 extends upwardly into the electrolysis chamber 17 and discharges through a self-regulating tioat valve, indicated diagrammatically at 84, and suitably of the type described in iFlG. 5 of my said U.S. patent. At the right-hand end of the cell body 10, there is provided a transverse wall 38 extending between the side walls of the cell body and engaged by the cover 30 to define the downstream end of the electrolysis chamber proper and to define an end compartment 89. The cell Ibottom slopes downwardly in the vicinity of the transverse wall 88 in order to form a well 90` into which the wall can extend to form a liquid seal against passage of the lighter electrolyte into the end compartment as long as the liquid level of the cathode is maintained.

The end compartment 89 is formed with an outlet opening 92. A tall cylindrical sleeve 94 is provided with apertures 95' and with a nose 96 normally disposed in outlet opening 92, the cathode level being maintained by the apertures 95 through which the alloy formed in the cell is discharged. The upper end of the sleeve 94 extends into a recess in cover 30 and it may be lifted, e.g. by electro-magnetic means, to permit emptying of the cathode from the cell, as described in my said U.S. patent. Suitable electrical insulation (not shown) prevents contact between sleeve 94 and cover 30.

From the cell outlet, the lead-alkali -metal alloy is conducted in molten form to a vaporizer 120, which may he of any desired form but is suitably a simple distillation unit conveniently heated by means of gas, oil or the like, in conventional manner. As indicated previously, vaporization of sodium or other alkali metal may be effected without further application of heat to the molten alloy by reducing the pressure in the vaporizer 120. This is suitably etected by connecting the vaporizer to any conventional vacuum source. An entrainment eliminator 121,.

e.g. a separator containing batlies or a cyclone-type separator is advantageously associated with the vaporizer toy remove any trace of particles of lead which may be mechanically entrained in the lead when the alkali metal is vaporized from it. The alloy arriving at the vapon'zer is already at an elevated temperature, i.e. at about 850 C. 'm the case of a sodium-lead alloy, and only a slight additional amount of heat needs to be added to effect the desired vaporizaton, i.e. to raise it to a temperature of about 890 C. in vaporization at atmospheric pressure, for example. In the case of a lead-potassium alloy, the alloy will come from the cell at a temperature in the neighborhood of 720 C. and it will have to be heated only to about 760 C. to bring about the desired vaporization of potassium at atmospheric pressure. The alkali metal vapors enter the vapor conduit 122 and are conducted to the oxidation chamber V125.

It is not, of course, necessary to vaporize all of the alkali metal from the alloy and, indeed, it is not desired to do so, but it is readily possible to vaporize at least about 25% of the alkali metal content of the alloy and, preferably, not more than about 50% of the alkali metal content. After the vaporization step the cathode stream is passed through the conduit 127 to the fuser 130 wherein the salt to be elcctrolyzed is liquefied so that it Will tlow into the cell. The fuser is suitably heated by any convenient heating means, e.g. gas or electricity, and the molten lead further assists, by heat transfer, in the melting of the salt in the fuser through which conduit 127 passes as it merges with the conduit 80 which leads from the lower portion of the fuser.

The fuser can be a simple kettle heated by gas or other means, as mentioned, into which the alkali metal salt is charged at the top and from the lower portion of which the molten salt is withdrawn. Thus the molten salt passes into conduit 82 substantially free from air and moisture. The molten lead is similarly substantially free from air and moisture.

Electrolysis is also carried out in the absence of air and moisture, suicient current being supplied to eiect the desired electrolysis reaction.

The alloy subjected to vaporization may have any desired content of alkali metal, and alkali metals such as sodium and potassium form alloys with lead of a wide range of proportions, but preferably the alkali metal content is at least about 10% and such an alloy can be readily produced by the process of my said U.S. patent and by the process described below.

In a typical operation in accordance with this invention, molten sodium chloride at 820 C. is supplied to the electrolysis chamber at the rate of 12 pounds per minute and the lead cathode at the same temperature is introduced at the rate of 45 pounds per minute. Electrolysis is carried out with D.C. current of 150,000 amperes at 4.5 volts and sodium combines with the lead cathode at the rate of 4.5 pounds per minute to form an alloy containing about 10% sodium by weight. This alloy having a temperature of about 850 C. is Withdrawn from the cell at the rate of 49.5 pounds per minute and is heated in the vaporizer to a temperature ot 890 C. to form sodium Vapor at the rate of about 2.25 pounds per minute by evaporating about 50% of the sodium content from the lead to leave an alloy containing about sodium for return to the cell.

Similarly, corresponding conditions and quantities are employed in converting molten potassium chloride into a lead-potassium alloy. In the case of the making of a potassium alloy, the temperature in the electrolysis zone is of the order of 720 C. and the alloy leaves the cell at about this temperature and, as previously mentioned, it will have to be heated only to about 760 C. to bring about the desired vaporization at atmospheric pressure.

As previously indicated, lead-alloys of varying alkali metal content may be employed but generally they will have an alkali metal content of about l0 to 50% by weight of the total alloy for best results. The content of the alloy can be regulated by the current applied in the cell. Thus, a lesser current will produce a lower alkali metal content and a greater current will produce an increased alkali metal content. Such variation in currents Wil be readily understood by persons skilled in the art.

The oxidizing chamber 12,5 is of any convenient form but, as seen in FIG. 2, is is advantageously in the form of a cylindrical chamber member 135 having an outlet 136 and surrounded with a cooling jacket 13S into which any suitable heat transfer medium, e.g. water, may be circulated through circulating conduits 139 and 140. Interiorly, the reaction chamber 125 is formed with bailles 142, suitably of channel shape, which dene a rst stage separator of the solid product produced, and the outlet 136 is suitably connected to a cyclone separator (not shown) to collect any solid particles which are not trapped in the first stage separator. Beyond the cyclone, there is suitably provided an eaust collector (not shown) and the exhaust gases may be passed into water to eliminate any entrained product from them before they are discharged into the atmosphere.

As the product is formed in the reaction chamber 125, it will fall to the bottom Wall of the chamber which slopes downwardly toward a product outlet which, by suitable conduits (not shown), will conduct the product to storage or packaging.

The oxygen-containing stream is introduced through an inlet line 148 and, since it is important to use completely dry air or other oxygen-containing gas, the inlet line 14S leading to the compressor 150 is suitably provided with a dryer, e.g. a calcium chloride dryer, indicated at 152, or a train of such dryers. The dryer must be effective to remove all moisture.

While air is preferably used as the source of oxygen for the oxidation reaction, it will be understood that pure oxygen or other mixtures of oxygen with inert gases may be employed. In any case, the entering gas stream must be dry.

As shown in FIG. 2, there is provided directly in the reaction chamber an inlet device in the form ot a jet injector in which the entering alkali metal vapors and the entering oxygen or oxygen-containing gas, e.g. air, are mixed and then introduced into the reaction chamber. This inlet device is indicated generally at 156. Thus, the inlet device has an axial inlet for the oxygen, which is suitably supplied under positive pressure from any convenient source, as from the compressor 150, and a lateral inlet 162 connected to inlet conduit 122 leading from the alkali metal vaporizer. Any jet injector construction is generally suitable for the purposes of this invention, but there is shown in FIG. 3 a jet injector construction which is particularly effective. As seen in FIG. 3, the inlet 160, into which the oxygen is introduced, is provided with a freely rotatable bladed rotor which rotates in response to the movement of the entering gaseous stream and serves to give it a swirling motion. The inlet channel terminates in a converging frustoconical portion which discharges into an outlet conduit 172 having a converging inlet portion and a diverging outlet portion. The junction between the converging 'end of the inlet and the converging portion of the outlet is found in a chamber 174 communicating directly with the lateral inlet 162. As the oxygen gas passes axially through the device, the suction created draws the vapor into the chamber 174 and effects intimate admixture between the two entering streams so that a mixed stream is injected into the reaction chamber.

The oxygen may be supplied at any desired pressure and a pressure reducing valve 1801 is suitably provided in the oxygen line in order to control the flow of the gas. To produce alkali metal oxides, stoichiometric quantities of oxygen tand alkali metal vapor are introduced into the reaction chamber and such stoichiometric quantities are readily obtained and maintained by control of 'the reducing valve, since the quantity of vapor drawn into the reaction chamber by the oxygen stream will depend upon the pressure of the gas entering the axial inlet 160. In practice, the oxygen stream will suitably be introduced at a pressure of about 2 lbs. gage at room temperature and will thus be relatively cool in relation t0 the temperature of the alkali metal vapor. The temperature of the reaction can vary over a wide range and, since the reaction itself is exothermic, the introduction of relatively cool oxygen gas has a moderating effect and helps to prevent the temperature from becoming excessive, thereby reducing the work that needs to be done by the coolant in the reactor jacket.

Particularly eiective control of the ratio between the 4oxygen and the alkali metal vapor can additionally be achieved by means of a valving mechanism in the jet injector shown in FIG. 3. Thus, as seen in this figure, in the chamber 171iare two concentric cylinder members and 186 which have their cylindrical surfaces closely disposed in relation to each other but which are spaced in relation to the walls of chamber 174 to leave an annular channel 188. The cylinder member 1315 is stationary and is secured to the walls of the chamber 174 in any convenient manner but the cylindrical member 186 is rotatable relatively to member 185 and this member is suitably guided in the end walls of the chamber 174, as in grooves 190. Rotation of the member 186 can be etected by any convenient actuating member (not shown) extending through the wall of the chamber 174 by `a flexible connection, or the like. As seen in FIG. 3, each of the cylindrical members 185 and 186 is formed -with a series of circumferentially-spaced apertures 192 which are aligned axially with respect to the cylindrical members but which can be shifted circumferentially relatively to each other, by suitable partial rotation of member 186, to control the size of the opening through which the vapor entering through the inlet 162 can pass into the interior of chamber 174 enclosed by the cylindrical members 135 and 186.

The alkali metal vapor enters the reaction chamber at a temperature above the boiling point of the particular alkali metal, e.g. 890 C. in the case of sodium and about 760 in the case of potassium. There is no need for further application of heat and, as mentioned above, the reaction is exothermic and the entering oxygen stream serves as a cooling agent as well as a source of oxygen for the reaction.

The relative proportions between the oxygen and the entering alkali metal vapor selected will, of course, depend upon the oxide to be formed, and not only monoxides but dioxides, peroxides and other oxides can be readily formed merely by control of the stoichiometric quantities of the entering oxygen and alkali metal vapors appropriate to the particular oxide desired. All calculations are, of course, made on the basis of pure oxygen and when air or other oxygen-containing mixture is used, the inert componen-ts of the entering gas stream need to be taken into consideration in selecting the volume of the stream. Air is preferred in all cases since its use facilitates control of the mixing operation.

Thus, in a typical operation for forming sodium monoxide, the sodium vapor stream enters at 890 C. and the dry air stream enters at room temperature, e.g. 25 C. The sodium vapor stream is introduced at the rate of 4.5 lbs. per min. and the dry air stream (20% oxygen) is introduced at the rate of 7.5 lbs per min. This will produce 6.065 lbs/min. of sodium monoxide. In the case of sodium peroxide, .the sodium vapor `will be introduced at the rate of 4.5 lbs/min. and dry air (20% oxygen) will be introduced at the rate of l lbs/min. to produce 7.63 pounds/min. of sodium peroxide, cooling being eected to keep the temperature in the reaction chamber below l000 C. Appropriate quantities for other oxides of sodium and for the oxides of the other alkali metals, e.g. potassium, can be readily determined by simple calculation based upon the stoichiometric quantities applicable to the particular oxide.

As previously mentioned the temperature in the oxidizing zone may vary widely and any temperature above the boiling point of the alkali metal vapor may be ernployed. However, the reaction being exothermic, the temperature tends to rise and it is desirable from a practical standpoint to prevent excessive temperatures, e.g. temperatures above about 1000 C. Control of temperature is achieved by introducing a cool oxygen-containing stream and by means of the coolant in the jacket 138, as mentioned. The oxygen stream may not only be introduced at room temperature but may even be precooled, if desired, e.g. to 0 C., as by passing it through a refrigerating unit (not shown) of any conventional type. Particularly advantageous results are achieved by cooling the baies 142 in the oxidizing chamber. Thus, as seen in FIG. 4, the baffles are `suitably formed as double walled channels having spaced-apart inner and outer walls 190 and 191 with an intermediate space 192 for receiving a coolant. The bales extend through the walls of the oxidizing chamber and their open ends communicate with the interior of the jacket so that the coolant in the jacket 138 will also pass through the intermediate space 192 in each baille. The coolant is introduced into the jacket under positive pressure and will effectively flow over all of the surfaces exposed to it. In this construction, the preferred coolant is liquid sodium. The reaction chamber, the jacket, the baffles and the related portions of the apparatus are, of course, formed from materials which are resistant to sodium, e.g. nickel alloys or any one of many known materials having such resistance.

It will be understood that Ivarious changes and modifications in addition to those indicated above may be made in the embodiments herein `described and shown in the drawings without departing from the scope of the invention as defined in the appended claims. It is intended, therefore, that all matter contained in the foregoing description and in the drawings shall be interpreted as illustrative only and not as limitative of the invention.

I claim:

l. The process of producing an alkali metal oxide which comprises electrolyzing a fused alkali metal salt in the presence of a fused lead cathode by causing said fused salt and said fused lead to flow through a horizontal electrolysis zone, whereby to form a molten alkali metal-lead alloy, passing the alloy from the electrolysis zone into a vaporizing zone while in molten heated form and directly evaporating the alkali metal from the alloy as a vapor of metallic alkali metal, the amount of said alkali metal vaporized from said alloy being at most about 50% of the alkali metal content of the alloy, and, without prior condensation of `said vapor, bringing said vapor into contact with a dry gas selected from the group consisting of oxygen and an oxygen-containing gas, said vapor being brought into contact with stoichiometric quantities of the dry oxygen contained in said dry gas, said alkali metal being brought into contact with said oxygen at a temperature above the boiling point of the alkali metal, whereby the alkali metal is wholly and continuously in vapor form, and introducing said oxygen and said alkali metal vapor into an oxidation zone maintained at a temperature above said boiling point but at most 1000o C.

2. A process as defined in claim 1, wherein said alkali metal salt is sodium chloride.

3. A process as defined in claim l, wherein said alkali metal salt is potassium chloride.

4. A process of producing an alkali metal oxide from a molten alkali metal-lead alloy which comprises passing the molten alkali into a vaporizing zone while in molten heated form and directly evaporating the alkali metal from the lead alloy as a vapor of metallic alkali metal, and, without prior condensation of said vapor, bringing said vapor into contact with a dry gas selected from the group consisting of oxygen and an oxygen-containing gas, said vapor being brought into contact with stoichiometric quantities of the dry oxygen contained in said dry gas, said alkali metal being brought into contact with said oxygen at a temperature above the boiling point of the alkali metal, whereby the alkali metal is wholly and continuously in vapor form, and introducing said oxygen and said alkali metal vapor into an oxidation zone maintained at a temperature above said boiling point but at most 1000la C.

5. A process as defined in claim l. wherein said alkali metal is sodium, said vapor is maintained at a temperature of at least about 890 C., and said dry gas is air, said air being at a substantially lower temperature than said vapor.

6. A process as defined in claim 1, wherein said alkali metal is potassium, said vapor is maintained at a temperature of at least about 760 C., and said dry gas is air, said air being at a substantially lower temperature than said vapor.

7. A process as defined in claim 4, wherein said alkali metal is sodium, said vapor is maintained at a temperature of at least about 890 C., and said, dry gas is air, said air being at a substantially lower temperature than said vapor.

References Cited in the le of this patent UNITED STATES PATENTS McNitt June 20, 1911 Jackson Aug. 13, 1946 10 FOREIGN PATENTS Great Britain 1912 Great Britain Apr. 14, 1954 Great Britain July 11, 1956 OTHER REFERENCES J. W. Mellors A Comprehensive Treatise on Inorganic and Theoretical Chemistry, volume 2, 1922, page 468;

Longmans, Green and Company, New York. 

1. THE PROCESS OF PRODUCING AN ALKALI METAL OXIDE WHICH COMPRISES ELECTROLYZING A FUSED ALKALI METAL SALT IN THE PRESENCE OF A FUSED LEAD CATHODE BY ASUING SAID FUSED SALT AND SAID FUSED LEAD TO FLOW THROUGH A HORIZONTAL ELECTROLYSIS ZONE, WHEREBY TO FORM A MOLTEN ALKALI MEATL-LEAD ALLOY, PASSING THE ALLOY FROM THE ELECTROLYSIS ZONE INTO A VAPORIZING ZONE WHILE IN MOLTEN HEATED FORM AND DIRECTLY EVAPORATING THE ALKALI METAL FROM THE ALLOY AS A VAPOR OF METALLIC ALKALI METAL, THE AMOUNT OF SAID ALKALI METAL VAPORIZED FROM SAID ALLOY BEING AT MOST ABOUT 50% OF THE ALKALI METAL CONTENT OF THE ALLOY, AND, WITHOUT PRIOR CONDENSATION OF SAID VAPOR, BRINGING SAID VAPOR INTO CONTACT WITH A DRY GAS SELECTED FROM THE GROUP CONSISTING OF OXYGEN AND AN OXYGEN-CONTAINING GAS, SAID VAPOR BEING BROUGHT INTO CONTACT WITH STOICHIOMETRIC QUANTITIES OF THE DRY OXYBEN CONTAINED IN SAID DRY GAS, SAID ALKALI METAL BEING BROUGHT INTO CONTACT WITH SAID OXYGEN AT A TEMPERATURE ABOVE THE BOILING POINT OF THE ALKALI METAL, WHEREBY THE ALKALI METAL IS WHOLLY AND CONTINUOUSLY IN VAPOR FORM, AND INTRODUCING SAID OXYGEN AND SAID ALKALI METAL VAPOR INTO AN OXIDATION ZONE MAINTAINED AT A TEMPERATURE ABOVE SAID BOILING POINT BUT AT MOST 1000*C. 